class Person{
  name: string;
  age: number;

  constructor(name: string, age: number){
    this.name = name
    this.age = age
  }

  show(){
    return `I am ${this.name}, I am ${this.age} years old.`
  }

}

class Student extends Person{
  gender: string;

  constructor(name: string, age: number, gender: string){
    super(name, age)
    this.gender = gender
  }

  show02(){
    return super.show() + `I am ${this.gender}`
  }
}

let s = new Student('zhangsan', 23, '女')
console.log(s.show02())
